The present invention relates to polyurethane-backed articles. The present invention particularly relates to polyurethane-backed articles and to a process and composition used in making same.
Articles having attached polyurethane foam layers are well known. For example, carpets and other substrates having attached polyurethane foam layers as backing are described in U.S. Pat. Nos.: 3,755,212; 3,821,130; 3,862,879; 4,022,941; 4,171,395; 4,278,482; 4,286,003; 4,296,159; 4,405,393; 4,483,894; 4,512,831; 4,515,646; 4,595,436; 4,611,044; 4,657,790; 4,696,849; 4,853,054; 4,853,280 and, 5,104,693. Typically a filler material is used to prepare a polyurethane formulation for carpet backing. The filler can replace some of the polymer required to prepare a polyurethane backed article, while maintaining bulk in the article. This can lower the cost of production of the article, since materials used as fillers are typically less expensive than the polymer material that is being replaced.
In selecting a filler for a particular application, the effect that the filler can have on the process--and on the physical properties of the article--should be considered. For example, in a process for preparing polyurethane backed carpets, a filler that is too alkaline can cause premature gellation. Conversely, a filler that is too acidic can cause an unacceptable delay in the onset of gellation. Increasing the amount of conventional fillers used in preparing carpet backing, such as calcium carbonate (CaCO.sub.3) and aluminum trihydrate (ATH), can result in an undesirable viscosity increase in a polyurethane formulation.
While cost reduction can be an incentive for introducing as much filler as possible into a polyurethane formulation, it can be unacceptable to reduce the cost of production at the expense of the quality of the article produced. The amount of filler incorporated into a polyurethane formulation can be limited by the adverse effects that the filler can have on the properties of a polyurethane, such as flexibility, resiliency, and adhesion, for example.
Fly ash has been used as a filler material in systems such as cement and concrete products, roadbases/subbases, and structural fills. See, for example, U.S. Department of Transportation/Federal Highway Administration Report No. FHWA-SA-94-081 (August 1995). The Electric Power Research Institute (EPRI), in EPRI Report CS-4765 (September 1986) (hereinafter CS-4765), reported that fly ash recovered from a direct acid leaching process was added as a filler to polymerized nylon and polypropylene.
It would be desirable to increase the loading of filler into a polyurethane formulation without detriment to the process of preparing a polyurethane carpet backing, or to the final physical properties of the final product. It would also be desirable to use fly ash as a filler material in a reactive polymeric system without significant effect on a polymer forming reaction.